1. Field of the Invention
The present invention relates to a method and apparatus for controlling a tool changer which comprises a changer arm for holding tools and is adapted to pivot the changer arm by a driving system including a servo motor to exchange a tool attached to a main spindle and a tool located in a predetermined position.
2. Description of the Prior Art
Tool changers employed for machine tools generally include a changer arm for holding tools, a rotation shaft connected to the changer arm in an orthogonal relation, driving means for axially moving the rotation shaft and rotating the rotation shaft about the axis thereof, and the like. In such a tool changer, the changer arm is moved axially of the rotation shaft and pivoted about the rotation shaft, and a tool attached to a main spindle and a tool located in a predetermined position are exchanged by such combined movement of the changer arm.
An electric motor (driving motor) is conventionally employed at least for the rotation of the rotation shaft. After the main spindle is moved to a tool changing position, the driving motor is driven and controlled so that the rotation shaft is rotated to pivot the changer arm.
In the field of machine tools, attempts are constantly made to reduce operation times of respective operating mechanisms to reduce a machining time for reduction of machining costs. The tool changer is also unexceptional, and an attempt is made to reduce the time required for tool change. Where the tool change is frequently carried out for machining, the tool changing time accounts for a great proportion of the total machining time. Therefore, the reduction in the tool changing time is imperative.
In view of the foregoing, the inventor of the present invention have conducted intensive studies to further reduce the tool changing time, and attained the present invention. It is therefore an object of the present invention to provide a tool changer controlling method and apparatus which can further reduce the tool changing time as compared with the prior art.